Multicast in a multi-protocol label switching (MPLS) environment.

The growth of multicast applications with high bandwidth, quality of service and availability constraints (e.g. IPTV, multipoint conferencing, games, etc.), and the need to encapsulate these multicast flows in tunnels to support multicast virtual private networks (VPNs), have led to the extension of MPLS (Multi Protocol Label Switching) technology ( ), initially defined for tunneling, traffic engineering and unicast security, to the transport of multicast flows ( ). The MPLS multicast architecture extends the MPLS switching mode to support MPLS LSPs (Label Switched Paths), with one source and several destinations, with replication on certain transit routers, enabling traffic to be broadcast so that only one copy of a packet is sent over a network link. These LSPs are called P2MP (point-to-multipoint) LSPs. The MPLS multicast architecture inherits the tunneling, traffic engineering and security properties of MPLS. It enables multicast traffic to be encapsulated in tunnels for VPN support, multicast tree optimization and fast multicast tree protection. This dossier presents the basic concepts of MPLS multicast technology and briefly discusses its application to IP multicast transport. It does not cover advanced MPLS multicast functions (routing in MPLS multicast VPNs, MPLS multipoint-to-multipoint, MPLS multicast hierarchy).

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